How can a teacher find other classes that would like to collaborate?

Here are a few resources:




Site
Description
Twitter
An indescribable site of constant communication.
Twitter 4 Teachers
An extensive list of educators on Twitter listed on a Wiki.
Twitter Hastags from Cybrary Man
A list of Twitter hastags to follow.
ePals
Collaboration opportunities for schools.
Edmodo Communities
Edmodo has several subjects in which teachers can connect with other teachers.
English Companion NING
Where English teachers can go to collaborate with each other.
Classroom 2.0
The social network for those educators interested in using Web 2.0 and social media in their classrooms.